Integrated circuits (ICs) are built up using a number of material layers. Materials selected for their electrical properties are deposited or grown on and within a semiconductor substrate. Using a process known as photolithography, each layer is patterned to add, remove or alter selected areas. A finished IC is therefore a substrate supporting a stack of patterned layers.
Modern ICs are complex and their development requires considerable effort and investment. Competitors can save considerable expense and move quickly to market by cloning extant ICs. Others may be interested in a gaining access to proprietary information that is stored or encoded in an IC.
Copyists have developed very sophisticated techniques for extracting proprietary designs and data. The patterned material layers are sequentially stripped and imaged. Software analyzes the resultant data to automatically recognize circuit features and their interconnectivity. Other inspection techniques can glean information about an IC by monitoring signals and field emissions of the IC in operation.
The process of extracting proprietary designs and data is commonly referred to as “reverse engineering.” Those interested in protecting their designs and data desire robust means of obstructing the reverse engineer.